Three-dimensional (3D) stereoscopic display technologies are currently under rapid development, and under the principle of 3D stereoscopic vision, two slightly different images are transmitted respectively to left and right eyes and extended reversely by the human eyes until the images are superposed and a stereoscopic “phantom” is observed to thereby generate stereoscopic sensation. Due to rapid development of the technologies, their corresponding standards and particularly test and evaluation standards, are relatively immature and fail to guide the evaluation of a 3D stereoscopic display effect during design and development of a 3D stereoscopic display product.
An experience purpose of 3D stereoscopic display is to generate “artificial” immersive experience feelings. Under the principle of 3D stereoscopic vision, two slightly different images are transmitted respectively to left and right eyes and extended reversely by the human eyes until the images are superposed and a stereoscopic “phantom” is observed to thereby generate stereoscopic sensation.
A stereoscopic phantom with a real scale has to be generated from the 3D stereoscopic display taking into account the following factors:
Firstly the size of a display screen greatly ranges from 26 inches to 32 inches, to 42 inches, to 50 inches, to 60 inches, to the size of a movie screen, and the entire screen is typically populated with the contents of an image. The image forms a phantom through both eyes, so the size of the phantom is proportional to the size of the screen and thus fails to be uniform. In this respect, if an optimum 3D display effect can be achieved on a 50-inch screen, there may be a sense of watching “Lilliput” on a 32-inch screen and watching “Brobdingnag” on a 70-inch screen.
Secondly a cameraman may embody artistic connotation from special angles of view such as bird's-eye view, bottom view and the like during photographing for the purpose of artistic process, and in this respect, whether to perceive the size of the phantom from the human vision perspective has become less important.
Thus the real scale of the stereoscopic phantom is more important then the real size thereof in the 3D stereoscopic display.
FIG. 1 is a schematic diagram of watching a stereoscopic image according to the related prior art. As illustrated in FIG. 1, when watching 3D stereoscopic display, human eyes typically are focused onto the perpendicular bisector of a screen. That is, the line of sight of the human eyes is perpendicular to the plane of the screen and projected thereon just at the central point of the screen.
Normally the scale distortion will not appear on the plane of a 2D screen perpendicular to the line of sight (as mentioned, the entire screen has been populated with the image, so the image will not be distorted in the 2D direction x-y as long as the aspect ratio of the screen, such as 16:9, keeps unchanged). However a 3D image may be, geometrically distorted in the direction z.
As illustrated in FIG. 1, the phantom may vary in location and size in the direction z when the human eyes move along the axis z. Specifically the phantom will be compressed in the direction z when the human eyes get close to the point “0”; and the phantom will be expanded in the direction z when the human eyes get away from the point “0”. The ratio of the compression to the expansion of the phantom is equal to the ratio of the compression to the expansion of the human eyes and the screen.
An effective solution has been absent so far to the problems in the prior art of geometrical distortion of the 3D stereoscopic image and a degraded effect of watching the 3D stereoscopic display due to restrictions of environmental factors and the like.